head to head
Marathon asks more than Team Fortress 2, and the gap is variance.

Execution · Competitive PvP
Aim duels against human crews layered over hidden-information loot gambles and extraction timing.

Execution · Competitive PvP
Class-based team shooter with deep mind games.
Marathon leans Execution (Competitive PvP); Team Fortress 2 leans Execution (Competitive PvP).
Marathon leans a little harder on execution, though the gap is small.
Marathon
Gunfights against other crews reward raw aim heavily
Team Fortress 2
Projectile aim and rocket jumps reward hands
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Marathon
Predicting human crews' rotations and ambushes is constant
Team Fortress 2
Spy/sniper duels are pure prediction
Marathon leans clearly harder on variance.
Marathon
Loot spawns and unseen squads create hidden information
Team Fortress 2
Random crits and spread inject RNG
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Marathon
Loadout economics and extraction routing sit underneath
Team Fortress 2
Class loadouts and map routes solvable
A matching score does not mean a matching test. Two games can both sit at 10 on execution and demand completely different things of you - which is why the reasoning above matters more than the number beside it.